Pre-release and unused content
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Pre-release and unused content definitions:
Pre-release elements should not be confused with unreleased media, entire games which never see release.
To some extent, this can apply to television shows and movies. For example, there were some early depictions of characters and deleted scenes found for the Super Mario Bros. film, which can be often found in the special features section of DVD releases.
The full list of pre-release content can be found here.